EGFR and cancer: Proportional allelic expression levels were found also for RAS and TP53 mutations, although one of the three patients with RAS mutations had higher relative expression of the mutated allele in the metastasis (ΔMAF RNA|DNA 0.49) than the primary tumor samples (range 0.07–0.31; Fig. 5d), suggesting selection for addiction to KRAS signaling and resistance to anti-EGFR therapy during metastasis of this cancer.